Porter has been out of action since Friday because of the injury, which began bothering him during the offseason. He was examined over the weekend and sought a second opinion from Birmingham, Ala.-based specialist Dr. James Andrews.

The Dolphins' first exhibition game is Saturday against Jacksonville. Porter would miss most or all of the preseason if he requires surgery.

"It's always good to get it done now if you have to," linebacker Zach Thomas said. "It's nothing serious. I've been in training camp, got a scope and came back two weeks later.

"I'd like for him to be here now, but to be honest, the season is much more important than right now. It's good he's taking care of that now, instead of waiting until the fourth or fifth game, and then he has to miss three or four games."

Another injury concern surfaced when tackle Anthony Alabi limped off the field today after hurting his left knee. He was to be evaluated.

Porter has missed only six games in his eight previous NFL seasons. Dolphins coach Cam Cameron declined to say whether he's concerned Porter might be sidelined for the entire preseason.

Porter wore a brace on the knee during offseason practices in early June. He took part in training camp when drills began July 28 but hasn't practiced since Friday morning.

Donnie Spragan would fill in for Porter. Spragan started nine games each of the past two years, then re-signed with Miami as a free agent in April.

"When we re-signed Donnie Spragan, that was a huge plus," Cameron said. "He understands the defense. He's a bright guy."